Method and apparatus for controlling concentration



y 1942- A. F. KALMAR ETAL 0,

METHOD AND APPARATUS FOR CONTROLLING CONCENTRATION Filed Jan. 20, 1940 5Sheets-Sheet 1 I July 21, 1942. A. KALMAR ETAL 2,290,473

METHOD AND APPARATUS FOR CONTROLLING CONCENTRATION Filed Jan. 20, 1949 5Sheets-Sheet 2 FIG; 3

42/7/02 1? M44142 Mil/4M e fiuwim/ July 21, 1942. A. RKALMAiR ETAL2,290,473 METHOD AND APPARATUS FOR CONTROLLING CONCENTRATION Filed Jan.20, 1940 5 Sheets-Sheet 3 H lllll H Illllllll WI fA/TUIPJ! Jury 21,1942. A. F. KALMAR EI'AL METHOD AND APPARATUS FOR CONTROLLINGCONCENTRATION Filed Jan. 20, 1940 S'SheetS-Sheet 4 W/ZLMM 17 J y 1942-A.. F. KALMAR ETAL 2,290,473

METHOD AND APPARATUS FOR CONTROLLING CONCENTRATION Filed Jan. 20, 1940 5Sheets-Sheet 5 RECTIflEE Patented July 21, 1942 UNITED STATES PATENToFFlca METHOD AND APPARATUS FOR CONTROL- LING CONCENTRATION Arthur F.Kalmar and William R. Huguenin, Riverside, Calif., assignors to FoodMachinery Corporation, San Jose, Calif., a corporation of DelawareApplication January 20, 1940, Serial No. 314,774

11 Claims.

be operated to maintain an accurate control of the concentration of gasin efiecting such treatments of fresh farm produce in widely varyingtemperatures, and particularly in relatively low temperatures such asare met with in refrigerator cars.

The manner of accomplishing the foregoing objects as well as furtherobjects and advantages of the present invention will be made manifest:

in the following description taken in connection with the accompanyingdrawings, in which Fig. l is a diagrammatic longitudinal sectional viewtaken on the plane ll of Fig. 2 and showing a refrigerator car packedwith boxes of citrus fruit and being gassed by a gas generatorcomprising a preferred embodiment of the apparatus of our invention.

Fig. 2 is a horizontal sectional view taken on the plane 2--2 of Fig. 1.

Fig. 3 is an enlarged side elevational view of said generator, partlybroken away to illustrate certain details of its structure.

Fig. 4 is a vertical sectional view taken on the plane 4-4 of Fig. 3.

Fig. 5 is an enlarged horizontal sectional view of the capillary testingliquid discharge tube of said generator and the heating elementassociated therewith and is taken on the. plane 5-5 of Fig. 4.

Fig. 6 is an enlarged horizontal sectional view of the atmosphere filterof the treating liquid container of said generator and is taken on theplane 6-6 of Fig. 4.

Fig. 7 is an enlarged vertical sectional view taken on the plane 7-! ofFig. 3.

Fig. 8 is a fragmentary detail sectional view taken on the plane 88 ofFig.7.

Fig. 9 is an enlarged fragmentary detail sectional view taken throughthe magnetic gas forming chemical supply and control valves of saidgenerator.

Fig 10 is an enlarged detail sectional view of 55 the lower portion ofone 01' said magnetic valves and is taken on the plane Ill-I0 of Fig. 9.

Fig. 11 is an enlarged longitudinal vertical sec: tional view takenthrough the scanning cell of said generator.

Fig. 12 is a transverse vertical sectional view taken on the plane l2|2of Fig. 11.

Fig. 13 is a diagram of the wiring of said generator.

Fig. 14 is a diagrammatic vertical sectional view ofa modified form ofthe testing liquid supply tank of said generator.

Referring specifically to the drawings, a gas generator l0 comprising apreferred embodiment of the apparatus of the present invention is shownin Figs. land 2 as installed in the performance of the method of thisinvention in a refrigerator railway car II.

The refrigerator car II has a floor l2, a foraminous false floor l3producing a horizontal air passage i4 between these floors, side walls[5, a ceiling I6 and ice bunkers I! at opposite ends of the car.Transverse walls It! separate the ice bunkers H from the cargo chamberIQ of the car. The upper'edges of the walls I8 are spaced from theceiling Hi to provide air passageways 25 which are equipped with panels26 upon which are mounted electric fan 21 for causing a circulation ofair in the car It as indicated by arrows in Figs. 1 and 2 as for thepurpose of cooling a cargo 28 of boxes of fruit which may be loaded .inthe cargo chamber l9. The side walls l5 of the car have double doors 29through which the cargo 28 is loaded into the chamber I9.

The gas generator 10 This generator is designed with particular regardto make it convenient to transport it from place to place and tofacilitate its introduction into a car II on top of a cargo of fruit 28after this cargo has been loaded into the car. The apparatus istherefore provided with a wheeled truck 32 having a base '33 on which isfixed a handle 34 by which the truck may be manipulated/ The base 33isprovided with wooden cross bars 35, 36 and 31, the bars 35 and 35having notches 38 near their opposite ends as shown in Fig. 4. Thehandle 34 is preferably formed of a piece of bent tubing having oppositevertical portions connected by a cross tube 39. The gas generator It!includes a frame structure 40, a reservoir and valve unit 4| for holdingand dispensing gas producing chemicals; a mechanism 42 forintermittently testing the content of ing the generator tion of suchgas;

treating gas in the atmosphere surround- I8 and controlling theproducand a chemical mixer 43 having incorporated therewith a tank 44for storing chemicals which have been used up in the operation of thegas generator I8.

The frame structure 48 comprises two rectangular pipe frames 48 whichare disposedvertically in spaced relation and rigidly united by crosstubes 41, 48, 49, 58 and 5| (see Fig. 3). Bolted to lower members of theframes 48 are wooden shoes 52. The generator I8 is adapted to be set inplace on the truck 32 with the wooden shoes 52 resting in the notches38. When so positioned, the cross tube 38 and the cross bar 31 act asstops preventing endwise movement of the generator I8 on the truck 32.

The reservoir and valve unit 41 the pipe frames 48 as shown in Figs. 3and 4 so that the unit 4| may be rolled into proper assembled relationwith the balance of the gas generator I8. When the unit 4| is thusassembled with the rest of the generator I8, a dog 81 (see Fig. 3)provided on the bottom of the tank 58 engagesa spring latch 88 whichsnaps over thig idog and holds the unit 4| in place as shown The unit 4|includes a pair of magnetic valves 18 and 1| which are enclosed in acase 12 secured to the bottom of the tank 58, the valve 18 connectingwith the hypo tank 88 and the valve 1| connecting with the acid tank 8|.Each of the valves 18 and 1| has a tube 13 having a nippic 14 at itsupper endwhich extends through an aperture in the bottom of the tank 58and is secured in place. by an apertured cap 15. Screwed onto the lowerend of the tube 13 is a cap 18 having a duct 11 therein, the upper endof which provides a valve seat and which is normally closed by avalve-member 18 gravitating into closed relation with said seat. Thevalve member 18 has a core 19 formed of magnetic material so that when asolenoid 88 which surrounds the tube 13 is energized, the valve member18 is lifted, thereby opening the duct 11 and permitting liquid to flowdownwardly therethrough from out of the reservoir with which thisparticular valve is associated.

As seen in Fig. 10, each of the caps 18 has a nipple 8| and a needlevalve 82, the latter controlling the fiow of liquid, from the reservoirs88 and 8| and being adjusted to permit two parts of hypo-chlorite toflow to one part of acid, this being the proportion of these liquidsrequired for the formation of hypo-chlorous acid gas as describedhereinafter.

Connecting to each nipple 8| is a flexible rubber tube 83 having a glasselbow nipple 84. The solenoids 88 of the valves as to be simultaneouslyenergized by electricity supplied through a cable 85 at its free end.

18 and 1| are wired so having a plug 88 v 1 The testing mechanism 42Included in this mechanism is a flat tank 98 (see Figs. 3 and 4) whichis permanently mounted on the generator frame 48. This tank has a fillerhole 9| which is adapted to receive a stop 92. Mounted in a closedrecess 93 in the top of the tank 98 is an air filter 94, one end ofwhich opens outwardly to the atmosphere, the other end of which opensinwardly into the interior of this tank. The filter 94 comprises a coiltube which is filled with coarsely ground peach pit charcoal 85. Thebottom of the tank 98 has a hole 88 for receiving a plug 91, through themiddle of which is an aperture which snugly receives the upper end of aglass rod 98 having a capillary duct 98 formed throughoutthe lengththereof.

As shown in Figs. '4 and 5, the glass rod 98 is bent back on itself toform a U-shape, one end of this rod extending upwardly through thestopper 91 and the other end extending straight downwardly. The rod 98is provided with a coil of electric resistance wire I88 and this wire isd a body II8, which,

(see Fig. 4) Just then covered with a layerof insulating material I8I.

Also fixed permanently on the generator frame 48, just beneath the tank88, is a housing I84. Mounted inside the housing I84 on a panel I85 areboxes I88 and I81. The box I88 contains a conventional photo-electriccell I88, while the box I81 contains an Threaded openings H8 and III,see Fig. 11, are provided in the respective boxes I88 and I81 on theaxis of light passing from the lamp I89 to the photo-electric cell I88.Screwed into the hole H8 is a nipple II5 having a bonnet II8 which holdsin assembled relation therewith a cap III of a scanning cell I I8. Thescanning cell includes when screwed into the cap II1, forms a closedchamber I28 containing a light flltering'fluid I2I such as a saturatesolution of copper sulphate. The cap H1 and body 9 of the scanning cell8 are preferably formed of transparent corrosion resisting material suchas that put out by the Du Pont Company under the trade name of Lucite.formed in the body 9 of the scanning cell H8 is a scanning recess I24which is closed with a Lucite plug I25 and which, as shown in Fig. 12,has a tangent inlet opening I28, an overflow outlet I21, and a cleaningopening I28 normally closed by a plug I29. The threaded hole III in thebox I81 receives a sleeve I38, in which are mounted a series ofrectifying lenses I3I, causing rays of light originating in the lamp I89to pursue parallel paths through a central opening I32 in said sleeveand parallel with the light axis abovereferred to. Thus, these rays oflight travel'through the scanning cell H8 and impinge upon thephoto-electric cell I88.

Mounted in an upper wall of the housing I85 beneath the discharge end ofthe capillary duct 88 is a funnel I33 having a nipple I34 which extendsinto the housing and is connected by a rubber tube I35 to a nipple I38,the latter being screwed into an outer threaded portion outlet passageI21 has a nipple I31 which connects with a rubber tube I38, the'latterpassing through a hole I38 in the panel I85 and out of the housingthrough a hole I48 (see Fig. '1) with which this tube makes a snug,airtight fit.

Also mounted on the inside wall .of the houselectric exciter lamp I89.

Also

of the inlet opening I28 of the scanning cell I I8 as seen in Fig. 12.The overflow ing I04 is a single coil relay I, a double interlockingrelay I42, a rheostat I43 and a microamp relay I44, the latter beingsubstantially like the device disclosed in U. S. Letters Patent No.2,062,915, issued December 1, 1936, to A. H. Lamb.

The relay I4I shown diagrammatically in Fig. 13, includes a coil I45 foractuating a bell crank I46 which, when thus actuated, operates a switcharm I41 so as to cause the latter to engage one or the other of twostationary contacts I48 and I49.

The double interlocking relay I42 coils I55 and I56, the coil oted leverI51 and the coil I56 operating a latch lever I58. Operated by the leverI51 is a single switch arm I59 having a stationary contact I60.

The rheostat I43 (see Fig. 4) is actuated by a shaft I65 which extendsthrough the wall of the housing I04 and has a er I61 for graduatedadjustment of the rheostat.

The micro-amp relay I44 is shown diagrammatically in Fig. 13 andincludes a moving coil I68 to which an oscillating switch arm I 69 isfixed, the latter having a permanently magnetized contact I thereon.Positioned for en gagement with the contact I10 is a stationarypermanently magnetized contact I1I, the arm I 69 being normally urgedinto engagement with the contact I" as shown in Figs. 4 and 13 by a hairspring I12. The relay I44 also has a solenoid I having a verticallymovable core I16 for actuating a pair of fingers I11 in the manner andfor the purpose described in the aforesaid Lamb patent. As disclosed insaid patent, and as shown in Fig. 4 of this application, a pointer I18is provided so as to pivot about the same axis with the arm I69 forregistration selectively with one of a series of graduations I19. Thepointer I18 normally remains stationary and is adjustable manually toincrease or decrease the includes I55 operating a pivtension exerted onthe switch arm I69 by the hair spring I12.

Rigidly mounted on the housing I04 in spaced relation therewith for thepurpose of heat-insulating it from said housing, is a secondary housingI80, the interior of which is shown in Fig. 7. The housing I80 isprovided for containing all of those elements of the mechanism 42 whichtend to become heated with use so that the heat from these elements willnot be transferred to the delicate apparatus contained in the housingI04. The secondary housing I80 has mounted therein ,a transformer I8I arectifier I82 and a motor driven cam switch unit I83.

The transformer! (see Fig. 18) has primary and secondary windings I 84and I85. The rectifier I82 has terminals I86, I81, I88 and I89. Themotor switch unit I83 includes a synchronous electric motor I94 whichoperates through reduction gears I95 to drive a shaft I96 having camsI91, I98 and I99 mounted thereon. As shown in Fig. 8, these cams havelobes I91a I98a and I99a respectively. Below these cams are microswitches 201, 208 and 209 respectively, these switches being pivoted ona rod 2I0 as shown in Fig. 8 and being adjustable by screws 2.

Provided on the generator I0, in suitable position where it is exposedto the temperature of the atmosphere surrounding the generator, is athermostat 2I2, shown diagrammatically in Fig. 13.

The electric system of the generator I0 as shown in Fig. 13, includesfour separate circuits: a 110 v.-A. C. circuit obtained from knob I 66and a point- Power lines; a 10 v.-A. C. circuit obtained from thetransformer I8I; a 10 v.-D. C. circuit obtained from the rectifier I82;and a micro-amp" circuit generated by the photo-electric cell I 08,these four circuits now being described in the order above named.

The elements energized by the 110 v.-A. C. circuit include the primarycoil I84 of the transformer I8I and the motor I94. The 110 v.-A. C.current is supplied through lead wires 2I5 and 2I6 which lead to theprimary coil I 84 of the transformer I8I. Leading from the wires 2I5 and2I6 to the motor I94 are wires 2" and 2I8.

The current of the 10 v.-A. C. circuit is excited-in the secondary I85of the transformer I8I and this energizes the rectifier I82 and theexciter lamp I09. Connecting opposite ends of I42 is to be energized bythe 10 the secondary I95 with the terminals I68 and I89 of the rectifierare wires 2I9 and 220. Extending from the wire 2I9 to the light switch201 is a wire 22I; from this switch to the light I09 is a wire 222; andfrom the wire 220 to the light I09 is a wire 223.

The 10 v.-D. C. circuit receives its current from terminals I86 and I81of the rectifier I 82, this circuit energizing the solenoids of thevalves 10 and H, the solenoid I15 of the microamp relay I44, and thecoils I45, I55 and I56 of the relays I41 and I42.

Connecting one end of each of the valve solenoids 80 with the terminalsI01 of the rectifier I82 is a wire 224. The opposite ends of thesolenoids '80 are-connected to the switch arm I 59 by a wire 225. Thecircuit for energizing the solenoids 80 is completed by a wire 226extending from the terminal I60 to the rectifier terminal I86.

Connecting the rectifier terminal I86 to the contact I1I of the relayI44 is a wire 221. This wire also leads to one end of the solenoid I15of this relay. The I15 is connected by a wire 228, to one terminal ofthe reset switch 209, the other terminal of this switch being connectedwith the terminal I81 of the rectifier I82 by a wire 229. Connectingthestationary contacts I48 and I49 of the relay I with one end of each ofthe coils I55 and I56 of the relay I42 are wires 230 and 23Irespectively, the opposite ends of the coils I55 and I56 being jointlyconnected by a wire 232 to one terminal of the cam operated relay switch208, the other terminal of the latter being connected by a wire 233 'tothe rectifier terminal I81; Connecting one end of the coil I45 of therelay I to rectifier terminal I81 is a wire 234, the opposite end of thecoil I4I being connected to switch arm I69 of the.microamp relay I 44 bya wire 235. The position of the switch arm I41 of the relay I4Idetermines which of the two coils I55 .or I56 of the relay v.-D. C.circuit as hereinafter described.

The micro-amp circuit between the photoelectric cell I 08 and the relayI44 as seen in Fig. 13 comprises a pair of wires 236 and 231 leading tothe moving coil I68 of the relay I44, the wire 231 embracing therheostat I43.

Connecting the rectifier terminal I86 to the switch arm I41 of the relayMI is a wire 238. One terminal of the thermostatic switch H2 isconnected by a wire 240 to one end of the coil I00 while the otherterminal of this thermostat is connected by a wire 24I to the rectifierterminal I81. The opposite end of the coil I00 is conopposite end of thesolenoid tinually during nected bya wire 242 to the rectifier terminalI86.

Interposition d between the wire 248 and the wire 2 so as to cut out thethermostat 2|2 where this is desired, is a manually operated switch 243.

The chemical mixer 43 The mixer 43 comprises the cover for the tank 44and has formed therein a series of annular concentric recesses 248 andan annular recess 241 encircling these somewhat deeper than the others,there being drain holes 248 connecting the lowermost points in therecess 241 with the tank 44. Mounted in the mixer 43 to extend upwardlytherefrom on the axis of the recesses 248 and 241 is an acid resistingstem 258, having mounted thereon a series of cups The function of thegenerator I8 is to produce gas at such a rate as to maintainthe requiredI-and a head- I member 252, the latter being provided with suitablevertical holes in which the L nipples 84 may be loosely received asshown in Fig. 3. Thus, any liquids discharged from the nipples 84 areretained temporarily and mixed as they flow downwardly into and from'thecups 25I and the annular recesses 248. When these liquids finallygravitate to the recess 241, they drain through the drain holes 248 intothe tank 44 which is provided for the purpose of collecting spentchemicals used up in the performance of the process of our invention.

Formed integral with the tank 44 (seeFigs. 3

and '1) is a subordinate chemical reservoir 288' having a cover 28I,

the latter having an opening 282 downward into which the lower end ofthe tube I38 extends.

Operation. I

The gas generator I8 of our invention, as already pointed out, isespecially adapted for use in gassing a cargo of fresh farm products ina railway refrigerator car. Figs. 1 and 2 illustrate the process as thistakes place in the car II. This process may be performed before, afteror during the precooling of the cargo 28 of fresh fruit in the car.Whichever is the case, the'fan panels 28 are installed in the'openingsat the upper end of the walls I8 and electric power provided for thefans 21 so that these run conthe operation of the process to circulatethe atmosphere in the car as indicated by the arrows in Figs. 1 and 2.If it is desired to perform the process during the precooling of thecargo 28, the ice bunkers I1 are filled with cakes of ice so that theair in the cars is cooled as it passes through these bunkers. Theprocess of the invention is preferably carried on concurrently with theprecooling of the cargo 28 as double use is thus made of the time periodas well as the power required for driving the fans 21 for accomplishingthese processes.

As will be noted in Fig. 2, the fans 21 are preferably offset relativeto each other at opposite ends of the car so as to cause a rotary motionof the air in the space between the cargo-and the ceiling I8 of the car.This tends to give a wider diffusion to the treating gas which isproduced by the generator as-will be presently described.

' the objects of the process of our the gassing of fruits at varyingtemperatures including particularly those met with in precooling freshfarm produce. For the gassing process to be-efiective and yet not burnthe produce, the concentration of the gas must be maintained'uniformthroughout the storage space and within very narrow limits.

' seen in Fig. 9. At the same 'ing this in the concentration of gas inthe air in the car throughout the period which the process must becarried on to kill the decay organisms present on the fruit. To performthis function, the generator operates automatically in the followingmanner:

The generator is prepared for service before being installed in the car,by filling the tanks 88 and 8| with sodium hypo-chlorite solution andacid solution respectively, from thetanks 88 and 8I being valve membersprevented by the 18 which are normally closed as time, the tank 88 isfilled with a testing liquid which-is preferably a solution oforthotolidine. A cap 285, placed on the dischargeend of the capillarytube 88 as seen in Fig. 3 prevents the flow of orthotolidine when thegenerator I8 is not in use. The generator I8 is now ready to be placedin the refrigerator car. As one man generally has to handle thisgenerator alone, it is especially designed to be easily handled by oneman in placcar and removing it therefrom. When disassembling thegenerator to handle it in this manner, the plug 88 is removed from itssocket in the housing I84 which plug and socket constitute a connectionin the wires 224 and 225. The elbows 84 are slipped out of the holes forloosely receiving these in the head 252 of the chemical mixer 43. Thespring latch 88 is then lowered, and the reservoir and valve unit H islifted and set aside by the operator. The chemical mixer 48 with itsassociated tank 44 is now also removed as-a unit from the balance of thegenerator and set to one side.

Assuming that the cargo packed in the car II as shown in Figs. 1 and 2,and one pair of the car doors 28 left open, the operator removes fromthe truck 82 the balance of the generator which comprises the frame 48and, the testing mechanism 42, and inserts this through the open cardoor onto the top of the cargo in the position in which the generator isshown in these figures.

The chemical mixer 43, with its associated tank 44 is now lifted-by theoperamr and slid into place in the generator so as to rest on the framecross members 48 and 58 and be lodged back of the cross member 5|, theoperator taking care in this step to see to it that the lower end of therubber tube I38 extends downwardly through the opening provided in thecover 28I for the reservoir 288.

The operator now lifts the reservoir and valve mechanism H and insertsit through the space between the upper edge of the car door and theframe 48 so that the rollers 88 rest on this frame and rolls the unit 4|inwardly on the frame until the dog 81 moves into latching engagementwith the latch 88 as shown in Fig. 3. The operator then inserts the plug88 of the cable into the receptacle provided therefor on the housing I85and inserts the glass elbows 84 into the openings provided for these inthe head 252 of the chemical mixer stem 258.

The wires 2 I5 and 2I8 are led into the housing I84 through a cable 288having a plug 281 which is now plugged into as table -volt outlet so asto energize the generator I8.

The electrical circuit to the fans 21 which have previously beeninstalled in the car is now enercar as indicated flow of the solutions28 has now beenby the arrows in Figs. 1 and 2.

this gas, in any one The car doors 29 are now closed. the cablessupplying electricity to the fans and the gas Benerator passing throughthe space between the doors and being accommodated by the yieldablepacking usually provided for these doors.

The first thing which takes .place when the is that the testingmechanism 42 operates to open process of our invention is first set inoperation the magnetic valves HI-and II to permit hypotion ispractically complete and the exhausted.

mixture of solutions drains downwardly through the openings 248 into thetank 44.

As this'gas is produced, it is continually mixed with the atmosphere inthe car II by the-circulation of air therein so that the concentrationof part of this atmosphere, is the same as the concentration of gasinany other part of said atmosphere. As the production of gas continues,however, the concentration of gas everywhere in the atmosphere in thecar increases until it approaches that value at which it is desired thatthis concentration be maintained constant by the generator 10.

From the time the generator I is first set in operation, the testingmechanism 42 functions to test the concentration of gas in theatmosphere in the car at predetermined intervals, and

preferably about every two minutes. When mak-' ing each such test, themechanism 42 opens the valves and H or permits theseto remain open ifthe concentration of gas is below the desired concentration. on theother hand, it shuts these valves oii or allows them to remain closed itthe concentration of gas in the atmosphere in the car should exceed thisdesired concentration.

The first step of testing the concentration of gas in the atmosphere isaccomplished. by exposing uniform quantities of orthotolidine solutionto said atmosphere and dropping this solution through said atmosphere indroplets and then collecting it in the scanning cell 8. Due to itsexposure to said atmosphere containing hypochlorous acid gas, theorthotolidine changes color, the depth of this color varying in directproportion to the concentration of said gas in said atmosphere. In eachof these periodic tests which is automatically'carried out once everytwominutes by the mechanism 42, the exciter lamp I09 is illuminated so as lto cast a beam of light through the scanning cell H8 and against thephoto-electric cell I 08. The amount of light which reaches thephoto-electric cell is inversely proportionate to the depth of color inthe orthotolidine solution resting in the scanning cell H8. Thephoto-electric cell I08 generates a very small electric current whenexcited with a beam of light and the current thus generated'is in directproportion'to the strength of that beam of light. Thus, the currentgenerated by the photo-electric cell during each of the tests carriedout by the tolidine above this mechanism 62 is in inverse proportion tothe concentration of gas in the atmosphere in the car. The mechanism 42responds to the current thus generated by the photo-electric cell I08.

When this current is above a certain value (thereby indicating'adeficiency in the concentration of gas in the atmosphere in the car i Ithe magnetic valves 10 and II will beopened if previously closed, orthey will be maintained open if previously open, so that the productionof gas by the generator in will continue following this test, and duringthe period between this test and the next test.

When, during any of current produced by the photo-electric cell I08 isbelow a, certain value, thus indicating that the concentration'of gas inthe atmosphere in the car H exceeds the value at which "it is desired tomaintain this concentration, then the testing mechanism 42 functions toshut the valves 70 and II if these were previously open, or to maintainthem shut if they were previously shut. When these valves-are closed, ofcourse, the flow of chemical to the mixer 43 is stopped so that thegenerator l0 ceases to generate gas.

' We have found that this process as Just described gives an inaccuratecheck on the concentration of the gas when performed at widely varyingtemperatures, and particularly when performed at temperatures varyingbetween normal mid-day temperatures and the temperatures produced in arefrigerator car by precooling the fruit with a circulation of airthrough the car with iced bunkers. We also discovered that the dimcultyhere encountered was due to the degree of reaction by orthotolidine withthe hypo-chlorous acid gas fluctuating with these changes intemperatureduring operation of the process.

Our present invention, therefore, embracesithe step of maintaining theorthotolidine at a substantially uniform temperature as it is dischargedinto at least maintaining the orthotolidine at a temperature above acertain critical temperature below which the reaction of theorthotolidine to the gas in the atmosphere is not uniform. The criticaltemperature above which we have found it advisable to maintain theorthotolidine at the time it is discharged into contact with theatmosphere, is 70 F. We have found that reasonable variations in thetemperature of the orthopoint do not greatly influence the reaction ofthe orthotolidine to the gas in the atmosphere.

The resistance element I00 is-so designed that when constantly energizedwith a direct current of 10 volts it will supply suflicient heat to theorthotolidine flowing through the capillary tube 98 so that, when thegenerator I ll'is operating in an atmosphere having the lowesttemperature met with in precooling of railway cars, the orthotolidineflowing through this tube will be warmed to a temperature of over 70 F.When the heaterator I0 is used in atmospheric temperatures considerablyhigherthanthos met within precooling railway cars such, for instance, asin storage rooms, packing houses and the like, the orthotolidine passingthrough the capillary tube 98 will of course be heated to a somewhathigher temperature by the heater make any substantial diiference in thereaction of the orthotolidine to the gas in the atmosphere surroundingthe generator, so that the generator will still accurately respond tothe concentration of gas in the atmosphere to maintain this within thelimits necessary for giving adequate treatment to the fruit withoutburning the latter.

A. complete cycle of the operation of the genof these tests, the amountcontact with the atmosphere, or.

I00, but this 'Will not a erator I will now be described in detail. whenthe generator is first installed in the ear II as shown in Figs. 1 and2, and the car doors closed as hereinbefore described for theperformance of the process of our invention, all three of the electricalcircuits, to wit, the 110 v.A. C. circuit, the v.A. C. circuit and the10 v.D. C. circuit, are energized. This causes the electric motor I94 tocontinuously rotate the shaft I98 and the cams I91, I98 and I99 fixedthereon. The motor is so geared to this shaft that the latter preferablymakes one rotation every two minutes. During each revolution, the camlobes on the cams I91, I90 and I99 engage and temporarily close theswitches 201, 200 and 209 so as to effect a testing of the content oigas in the atmosphere in the car II, each such test being completedwithin a period of about ten seconds. As shown in Fig. 13, the lobe I91aof the cam I91 is larger than the lobes I90a and I99a. This causes theswitch 201 to close prior to the switches 208 and 209 and to remainclosed longer than the latter two. Closing the switch 201 closes the 10v.A. C. circuit to the exciter lamp I09 which throws a beam of lightthrough the scanning cell IIO, filter cell I20, and into thephoto-electric cell I08, the latter thus being caused to dischargeelectrical current which energizes the moving coil I68 of the relay I44.

Immediately after the lamp I09 is lighted by the closing of the switch201, the switch 209 is momentarily closed by the cam I99 to reset theswitch arm I69 of the micro-amp relay I44. Closing of the switch'200closes the 10 v.D. C. circuit from the rectifier I02 to the solenoid Iof the relay I44 and causes the core I19 of that solenoid to swing thefingers I11 inwardly, this centralizing the switch arm I09. Upon theopening of the switch 209 which immediately follows, the solenoid I15 isde-energized, the fingers I11 separate and the relay arm I00 isreleased.

When the moving coil I50 is energized by a current from thephoto-electric cell I00, the coil I50 tends to swing the switch arm I59rightward away from the magnetic contact "I against the influence of thehair spring I12. When the gas concentration in the car II is below thedesired minimum, the orthotolidine solution in the scanning cell H8 isrelatively clear, thus allowing a substantial amount of light to passfrom the lamp I09 to the photo-electric cell I00. The current generatedby the photo-electric cell I00 is thus sufllcient to cause the movingcoil I80 of the relay I44 to maintain the switch arm I09 out ofengagement with the: contact I", thus breaking the circuit to the coilI45 of the relay HI and permitting the switch arm I41 of the latter toremain in. contact with the terminal I40. When the switch arm I41 is inthis position, the circuit is closed through the wire 280 to the coilI55 of the relay I42 and when the cam operated switch 200 is closed bythe cam I88, the circuit from the rectifier I02 to the relay I42 iscompleted to energize the coil-I55. The latter is thus caused to movethe lever I51 which lifts the switch arm I59 upwardly against theterminal I60, thereby closing the electric circuit of the solenoids 00of the valves 10 and H. This lifts the valve members 18 and allows thehypo-chlorite and acid solutions to fiow downwardly through these valvesand be discharged from the glass elbows 04 into the chemical mixer 42,thereby producing hypo-chlorous acid gas as described hereinabove.

The lever I51 of the relay I42 is retained in operative position (afterthe circuit'to the coil I55 is broken), by the latch 'lever I50 in orderto maintain the valves 10 and H in open position. This results from thefact that the latch lever I50 is spring-biased'inwardlyas shown in Fig.13 and whenever the magnet I55 is not energized and the lever I51 isrotated by the energizing of the magnet I55, the latch lever I58 swingsinto place to hold the lever I51 in its rotated position in which itholds the switch arm I59 upwardly against the terminal I50.

As long as the concentration of gas in the car II is less than theminimum predetermined as desirable in the process of our invention, thegenerator I0, upon each succeeding testing operation as above described,operates in the same manner as set forth to retain the valves 10 and Hin open position.

When the concentration of gas in the car II exceeds the predeterminedmaximum allowable, the production of gas by the generator I0 is stoppedin the following manner:

The amount of gas now present in the air is suflicient to darken theorthotolidine dropping through the atmosphere to such a point. that whenthe latter flows down into the scanning cell and the next test takesplace, the amount of light transmitted through the scanning cell to thephoto-electric cell I08 is reduced and causes a proportional reductionin the amount of current generated by the cell I00. When the switch armI59 of the relay I44 is again centralized and subsequentlyrel'eased bythe finger I11 in response to the momentary closing of the switch 209,an insufficient amount of current is received by themoving coil I00 toovercome the force exerted on the switch arm I69 by the hair spring I12,whereupon the arm I59, when released by the arms I11, swings to theposition-in which it is shown in Fig. 13 with the contacts I10 and "I inengagement. The latter engagement closes the circuit from the rectifierI02 to the coil I45 of the relay I so as to actuate the lever I40 andmove the switch arm I41 into engagement with the terminal I40, thusjoining the wires 280 and 23I and enabling the coil I of the relay I42to be energized when the switch 200 is closed by the cam I90. When thecoil I58 is thus energized, the latch lever I50 is moved out ofengagement with the lever I51, causing the switch arm I59 to movedownwardly away from the contact I50 so as to break'the circuit to thevalves 10 and H and cause the latter to stop the flow of the gas formingliquids downwardly to the mixer 40.

Throughout the operation of our process, the checking of theconcentration of the gas in the atmosphere within the car II takes placeonce each two minutes as above described, and the gas-producingapparatus of the generator I0 is thus automatically controlled so as tomaintain said concentration within the necessary predetermined range ofvalues.

The rheostat I40 permits adjusting the generator I0 so as to vary therange of values which are maintained in the concentration of gas by thegenerator I0. This is done by regulating the amount of current permittedto pass from the pirrto-electric cell I00 to the micro-amp relay I Inthe preferred mode of operating the apparatus of our invention, theswitch 242 is closed so that the heating element I00 as heretoforedescribed is continuously energized. In case the process is to beperformed in an atmosphere the when the temperature of the atmosphere inwhich the process is being performed ishighenough so that heating of theorthotolidine solution is unnecessary, this is avoided,

Referring now to Fig. 14, a modified form of orthotolidine tank 300 isshown here, this tankbeing equipped with a heater 31", the supply ofcurrent to which is controlled by a thermostatic switch 302, both heaterand switch being sub merged in the orthotolidine in the tank. When usingthe tank 300 in the process of our invention, all of the orthotolidinein this tank is maintained at a temperature within the range where theorthotolidine will react uniformly when contacting the gas contained inthe atmosphere in which the process is being performed.

The herein disclosed process, while particularly useful in treatingcitrus fruits as specifically disclosed, is equally capable of broadapplication to edible or fresh farm products of all kinds ascontemplated in the specification. Therefore the term "fruit" as used inthe claims is not to be construed as limiting the claims to anypartlcular type of edible product. We claim:

1. In the gas treatment of fruit under varying temperature conditions,the method ofconfining said fruit in a chamber, liberating a treatinggas into the atmosphere within said chamber, passing through theatmosphere in said chamber a control agent of orthotolidine whichcontacts and reacts with saidgas, maintaining said control agent withina range of temperatures in which its reaction with-said gas will besubstantially uniformly in proportion to the concentration of said gasin said atmosphere regardless of the fluctuations in the temperature ofsaid atmosphere, testing the extent of said reaction between said gasand said control agent, and adjusting the concentration of said gas. insaid atmosphere in accordance with the reaction between said gas andsaid agent.

2. In the gas treatment of fruit under varying temperature conditions,the method of confining said fruit in a chamber, liberating a treatinggas into the atmosphere within said chamber, passing through theatmosphere in said chamber a control agent of orthotolidine whichcontacts and reacts with said gas, maintaining said agent within a rangeof temperatures in which its reaction with said gas will besubstantially uniformly in proportion to the concentration of said gasin said atmosphere regardless of the fluctuations in the temperature ofsaid atmosphere, periodically testing the extent of said reactionbetween said gas and said control agent, and

' adjusting, between successive tests, the'concentration of said gas insaid atmosphere as necessity for this is indicated in the latest of saidtests by the extent of said reaction between said gas and said agent.

3. In the gas treatment of fruit under varying temperature conditions,the method of confining said fruit in a chamber, liberating hypochlorous acid gas into the atmosphere within said chamber, passing asolution of orthotolidine through the atmosphere in said chamber,maintaining said orthotolidine within a range of temperatures in whichits reaction with said gas will be substantially uniformly in proportionto the concentration of said gas in said atmosphere regardless of thefluctuations in the temperature of said atmosphere, testing the extentof said reaction between said orthotolidine and the gas in saidatmosphere and adjusting the concentration of said gas in saidatmosphere as necessity for this is indicated by the extent of said resttion between said gas and'said orthotolidine;

.4; In the gas treatment of fruit under varying temperature conditions,the method of confining said fruit in a chamber, liberating hypochlorousacidgas into the atmosphere within said chamber, passing a solution oforthotolidine through the atmosphere in said chamber, maintaining saidorthotolidine within a range of temperatures of about F, to about F.,testing the extent of, the reaction between said orthotolidine and thegas in said atmosphere. and adjusting the concentration of said gas insaid .atmosphere as necessity for this is indicatedby the extent of saidreaction between said gas and said orthotolidine. I

5. In the gas treatment of fruit under vary- ,ing temperatureconditions, the method of confining said fruit in a chamber, liberatinghypochlorous. acid gas into the atmosphere in said chamber, passing asolutionv of orthotolidine through the atmosphere in said chamber,maintaining said orthotolidine at a temperature above 70 F., testing theextent of the reaction between said orthotolidine and the gas in saidatmosphere, and adjusting the concentration of said gas in saidatmosphere asnecessity for this is indicated by the extent 'of saidreaction between 'said gas and said orthotolidine.

6. In the preparation of fresh fruit for market.

the method of confining said fruit in a chamber,

setting up a circulation of theair in said chamber, cooling said air atone or more points in the circulation thereof, introducing moldinhibiting gas in said air at one or more points in the en,-

culation thereof, passing through the atmosphere in said chamber anorthotolidine control agent which contacts and reacts with said gas,maintaining said agent within a range of temperatures in which itsreaction withsaid gas will be substantially uniformly in proportion tothe concentration of said gas in said atmosphere, re-

gardless of the fluctuations in the temperature of said atmosphere,testing the extent of said reaction between said gas and said controlagent. and adjusting the concentration of said gas in said atmosphere asthe necessity for this is indicated by the extent of said reactionbetween said" gas andsaid agent.

7. An apparatus for gassing fruit comprising:

means for liberating a treating gas into the atmosphere surrounding saidfruit; means for exposing a testingliquidcontaining orthotolidine tosaid atmosphere for reaction with said gas; means for heating saidtesting liquid to maintain it within a range of temperatures which willprevent any substantial fluctuation of the reaction I between saidliquid and said gas in response to fluctuations in the temperature ofsaid atmosphere; and means automatically responsive to the reactionbetween said treating gas and said testing liquid for regulating theliberation of said gas in accordance with the degree of said reac-.

tion.

8. An apparatus for gassing fruit comprising:

means for liberating a treating gas into the surrounding atmosphere;means for exposing a testing liquid containing orthotolidine to saidatmos- 9. In an apparatus for use in the gas treat' ment of fruit undervarying tions, the combination of; chamber in which said fruit isadapted to be confined; means for liberating a treating gas into theatmosphere surrounding said fruit; means for holding a supply of liquidorthotolidine contemperature condit-rol agent which is adapted to reactwith said gas; a tube having a capillary duct therein for deliveringcontrol agent from said supply means to open and free contact with saidatmosphere; means for heating said tube to maintain the control agentdischarged therefrom within a range of temperatures in which thereaction between said agent and the gas in said atmosphere will besubstantially uniformly in proportion to the concentration of said gasin said atmosphere, regardless of the fluctuations in the temperature ofsaid atmosphere; automatic. means for testing the extent of saidreaction between said gas and said control agent; and means forautomatically varying the supply ofgas to said atmosphere in response tothe'extent of said reaction between the gas of said atmosphere and saidcontrol agent to maintain the concentration of said gas withinpredetermined limits.

10. In an apparatus for use in the gas treatment of fruit under varyingtemperature conditions, the combination'of: means for liberating atreating gas in the atmosphere surrounding said fruit; means for passingan orthotolidine control agent through said atmosphere while in freecontact with said atmosphere, said control agent being adapted to reactwith said gas; means for heating said control agent to maintain this atthe time it so contacts said atmosphere within a means iorming a rangeof temperatures in which the reaction between said control agent and thegas in said atmosphere will be substantially uniformly in proportion tothe concentration of said gas in said atmosphere, regardless of thefluctuations in the temperature of said atmosphere; automatic means fortesting the extent of said reaction between said gas and said controlagent; and means for automatically varying the supply of gas to saidatmosphere in response to the extent of said reaction between the gas ofsaid atmosphere and said control agent to maintain the concentration ofsaid gas within predetermined limits.

11. In anapparatus for use in the gas treatment of fruit under varyingtemperature conditions, the combination of: means for liberating atreating gas in the atmosphere surrounding said fruit; means for passingan orthotolidine control agent through said atmosphere while in freecontact with said atmosphere, said control agent being adapted to reactwith said gas; means for heating said control agent; thermostatic meansfor controlling said heating means to maintain said control agent at thetime it sb contacts said atmosphere within a range of temperatures inwhich the reaction between said control agent and the gas in saidatmosphere will be substantially uniformly in proportion to theconcentration of said gas in said atmosphere, regardless of thefluctuations in the temperature of said atmosphere; automatic means fortesting the extent of said reaction between said gas and saidcontrol'agent; and means for automatically varying the supply of gas tosaid atmosphere in response to the extent of said reaction between thegas of said atmosphere and said control agent to maintain theconcentration of said gas within predetermined limits.

ARTHURF. KALMAR. WILLIAM R. HUGUENIN.

